WO2009013193A1

WO2009013193A1 - Parking brake system and method for operating such a system

Info

Publication number: WO2009013193A1
Application number: PCT/EP2008/059278
Authority: WO
Inventors: Ralf Kersjes; Lothar Werner; Bernhard Schmittner; Heinz-Anton Schneider; Christof Maron
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2007-07-26
Filing date: 2008-07-16
Publication date: 2009-01-29
Also published as: US20100299035A1; EP2183133A1; DE102008033309A1

Abstract

A parking brake system for motor vehicles is described, having an operator control element and at least two electromechanical actuators (1, 2) for generating a parking brake force on in each case one wheel of the motor vehicle with in each case one wheel actuation unit (RCU1, RCU2) per electromechanical actuator and one further control unit (10'). In this context, the further control unit (10') is connected, on the one hand, to the operator control element and, on the other hand, parallel to each wheel actuation unit (RCU1, RCU2) via at least one parking brake data bus (11, 12). The further control unit (10') applies control signals to the wheel actuation units (RCU1, RCU2), and means (31, 32) are provided which ensure reliable operation of the parking brake system with wheel actuation units with in each case one microcontroller. These means (31, 32) ensure safe operation of the wheel actuation units within the parking brake even in the case of a communications fault in the parking brake data bus, and said means (31, 32) ensure that at least one actuator (1, 2) is actuated even in the case of a communications fault in the parking brake data bus of the parking brake system. In addition, a method for operating such a parking brake system is described.

Description

Parking brake system and method for operating such

The present invention relates to a parking brake system for motor vehicles with a control element and at least two electromechanical actuators for generating a parking brake force on each wheel of the motor vehicle and with at least one Radansteuerungseinheit and another control unit. The invention further relates to a method for operating such a parking brake system.

Parking brake systems for motor vehicles which are actuated by electromechanical actuators are known as electric parking brake or EPB for short. Such a parking brake has an operating element, for example a switch button, which enables the parking brake to be actuated by means of a small amount of force. So far parking brake systems are usually as shown schematically in Figure 1, constructed. The parking brake system has a central electronic control unit 4, which is connected on the one hand to the vehicle bus 5 and the operating element, not shown, and on the other hand energized the actuators 1, 2 at the corresponding braking devices independently of each other via the respective power supplies 3 and 6. Accordingly, the respective parking brake is closed or opened. The failure of an actuator 1.2 thus has no effect on the controllability of the other actuator 1.2.

In the context of cost optimization, it is envisaged to dissolve the central control unit for the actuators and to allow the functionality of the central control unit to be executed at least partially by means of vehicle control units already present in the vehicle, which also fulfill other functions.

One possibility for a division of the central control unit of a vehicle brake system is described in the publication WO 2007/014952 Al. Each electromechanically operable wheel brake is in each case assigned to its own control and regulation unit.

Another solution is from the publication

DE 100 06 656 Cl known. In the motor vehicle, a so-called BAF control unit (Bremsassistenzfunktions- control unit) is provided, to which the parking brake request the driver is transmitted from the control. The BAF control unit also controls one or more of the functions of the electric stability program, traction control and the differential lock. If the vehicle speed is within a certain speed range, the braking means associated with the parking brake are activated both by the EPB control unit and by the BAF control unit, wherein braking pressures or braking forces are generated by the BAF control unit depending on the braking effect achieved by the EPB control unit , Below the said speed range, the parking brake is actuated only by the EPB control unit, so that this control unit must be equipped with the full functionality for an actuator drive and a cost savings in terms of ECU execution is not achieved.

In addition, three signal lines are provided in the parking brake system known from DE 100 06 656 Cl, wherein the first signal line control element and EPB control unit, the second signal line control element and BAF control unit and the third signal line connects the two control units together. A parking brake request signaled by actuation of the control element is transmitted via the third signal line from the EPB control unit to the BAF control unit. Since each control unit controls an electromechanical actuator, a proper operation of the parking brake system is no longer possible in the event of failure of one of the two control units. - A -

When realizing the functional scope of the central control unit in a control unit of the motor vehicle, which performs other functions, there is the problem that the electromechanical actuator must be provided with a controllable power supply. If the control unit, which also carries out other functions, is too far away from the actuator to be controlled, an optimal power supply to the actuator is no longer possible without restriction due to the large losses along the line path.

Therefore, the division of the functionality of the central control unit is now provided such that a simplified logical range of functions of the central control unit is relocated to vehicle control units, which fulfill other functions, and that a significant portion of the control logic of the actuators, in particular the control of the power supply, into a so-called Radansteuerungseinheit (hereinafter RCU called) to relocate, which is arranged in the spatial proximity of the actuators.

The housed in the Radansteuerungseinheit wheel electronics for electromechanical actuators parking brakes consists of a power electronics and a control unit. On the one hand, the electric power supplied to the electromechanical actuators is controlled and switched by the wheel drive unit, and on the other hand processing of the supplied signals as well as generation of simple new signals takes place. For the signal or data processing and for the actual Voltage control of the individual actuator are provided one or more microcontroller. The combination of electromechanical actuator and wheel electronics is also referred to as "Smart Actuator".

Since the parking brake is a central for the safety of the motor vehicle or occupant device, it is necessary in such a division of the actuator control to ensure a partial actuation of the parking brake even in case of errors in data transmission or power supply of a "smart actuator". In the parking brake system according to FIG. 1, it is also possible, for example, to control the other one even if one actuator fails.

For the operation of a moving vehicle certain malfunction of a single actuator can be critical to safety. Here, in particular, mention should be made of the unintentional tightening of a single actuator while driving, which may be e.g. could be done by a single error in a single microcontroller of a "smart actuator". To avoid this error, a second microcontroller can be provided as redundancy in the "Smart Actuator". However, this solution is very expensive.

Alternatively, a switch can be provided in the "Smart Actuator", which is switched by a drive unit outside of the "Smart Actuator" and thus allows only a control of the actuators and thus applying the parking brake. This solution is disadvantageous. The object of the present invention is therefore to provide a parking brake system for motor vehicles, in which the operation of at least one actuator in case of failure is possible at any time, as it is also realized in the known system of Figure 1. The object is also to provide a corresponding method for operating a parking brake system.

The above object is achieved by a parking brake system in which each electromechanical actuator is provided with a Radansteuerungseinheit, the further control unit (hereinafter also called ECU) on the one hand to the control element and on the other hand via at least one parking brake data bus connected in parallel with each Radansteuerungseinheit wherein the further control unit acts on the Radansteuerungseinheiten with control signals and wherein means are provided which ensure the actuation of at least one actuator, even in the event of a communication failure in the system of the parking brake system. Each actuator is in this case preferably connected to a separate, only for this actuator active Radansteuerungseinheit.

By provided in the parking brake system according to the invention interconnection of the controls and the means for actuating at least one actuator safe operation of the parking brake system can be ensured even in case of failure. In this case, the functionality comprising the further control unit is integrated into a control, which also includes other control functions of the motor vehicle includes, for example, the ESP control (ESP = Electronic Stability Program).

In a first embodiment of the invention, at least one safety data bus is provided as means for ensuring the actuation of the actuator, which connects the further control unit parallel to the parking brake data bus with each Radansteuerungseinheit (RCU). In the event of failure of the parking brake data bus, it is thus ensured that actuation of the actuators via the further control unit (ECU) can continue via the safety data bus.

In a second, alternative exemplary embodiment, at least one control / emergency control line is provided as means for ensuring the actuation of the actuator, which connects the further control unit (ECU) parallel to the parking brake data bus with a Radansteuerungseinheit (RCU). Preferably, two control / emergency control lines are provided, wherein each control / emergency control line connects the further control unit, each with a Radansteuerungseinheit.

The control / emergency control line is used in normal operation as a logical safeguard of the parking brake data bus and each of the Radansteuerungseinheit contained single microcontroller. In the event of an error in the parking brake data bus, the signals transmitted via the control / emergency control line additionally serve as input variables in a logical actuator enable circuit which is provided in the respective wheel drive unit. This allows the parking brake system to operate safely, with each wheel Control unit requires only a single microcontroller.

In the event of a communication failure between further control unit and Radansteuerungseinheit this control / emergency control line is acted upon with a simple logical data protocol, which makes it possible to control the individual actuators / Radansteuerseinheiten without the connection to the parking brake data bus. This solution is also a more cost-effective compared to the first embodiment variant, since no further data bus must be provided, but only a simple electrical connection line.

The further control unit preferably has means which, in an emergency operation, preferably in the event of a failure of the parking brake data bus, transmit a safety signal sequence (signal code) to the wheel drive control unit via the control / emergency control line. In the case of fault operation, therefore, a simple logical signal (safety signal sequence) is generated, which to a certain extent announces (triggers) the actuation of the respective actuator by the wheel drive control unit. The subsequent high signal on the control / emergency control line (eg a defined current level), serves as continuous power for a discrete period, for example about 2 seconds, to enable the respective actuator, so that by the microcontroller of the Radansteuerungseinheit immediately the application of the associated Parking brake is effected. The actuation of the actuator by the Radansteuerungseinheit thus takes place after receipt of the high signal at the input of the respective Radansteuerungs- unit.

For this purpose, each Radansteuerungseinheit in a preferred embodiment of the parking brake system according to the invention on means which receive the safety signal sequence at the input of the control / emergency control line and then verify it and allow for a positive Verifikationsergebnis an actuator.

To prevent manipulative intrusion into the parking brake system from the outside, the simple logical data protocol (security burst) may also be chosen such that the logic is subject to time-varying coding, i. is temporally changeable. For example, the code may be selected depending on the system time, generated via a random generator, or communicated over the parking brake data bus (if it is still operating correctly). In the latter case, the safety signal sequence is selected in case of failure of the parking brake data bus such that it corresponds to the signal sequence, which was last communicated before the failure.

In a further preferred embodiment of the invention, each Radansteuerungseinheit has means which generate after the actuation of the actuator a confirmation signal sequence (confirmation signal code), wherein the confirmation signal sequence via the respective control / emergency control line to the further control unit is sendable. By means of the confirmation signal sequence, the driver of the motor vehicle or other functionalities of the Motor vehicle informed of the successful operation of the parking brake.

In order to be able to generate the described safety signal sequences, the further control unit and optionally each wheel drive unit preferably have means for signal sequence generation of an electrical signal.

The above object is also achieved by a method for operating a parking brake system, which carries out the following steps:

- monitoring communication in the parking brake system and initiating emergency operation if a communication fault, e.g. on the parking brake data bus, it is determined

- Inserting the means for actuating at least one actuator in emergency operation when the driver actuates the operating element and / or the motor vehicle is.

The inventive method ensures that the parking brake system retains its functionality even then, i. at least one actuator can be operated when a communication failure occurs in the system.

The emergency operation preferably comprises the acceptance and execution of the communication between the further control unit and each wheel drive unit by the safety data bus. This emergency operation can be carried out in the case when a second data bus, namely the Safety data bus is provided in parallel to the parking brake data bus.

Alternatively, the emergency operation includes the adoption and implementation of the communication between the further control unit (ECU) and each Radansteuerungseinheit through the at least one control / emergency control line. This is a particularly simple method which is feasible if at least one control / emergency control line is provided, which connects each Radansteuerungseinheit with the other control unit.

Preferably, in the latter case, if the operating element is actuated by the driver and / or the motor vehicle is stationary, then a safety signal sequence is subsequently transmitted by the further control unit and then over a certain fixed period of time, preferably over at least about 2 seconds. Signal generated and sent via the at least one control / emergency control line to the respective Radansteuerungseinheit. By this combination of the generated and transmitted to the Radansteuerungseinheit signals on the one hand, the actuator is initiated (by the safety signal sequence) and then also allows (by the high signal).

In a preferred embodiment, each Radansteuerungseinheit verifies after receipt of the safety signal sequence through the input of the user line this and allows for a positive verification result an actuator operation, which is then subsequently made possible by the high signal. It is further preferred if the Radansteuerungseinheit generates a signal sequence after completion of the actuation of the respective actuator, which is sent via the at least one control / emergency control line to the further control unit and represents an acknowledgment of Aktuatorbetätigung. As a result, the driver can also be given feedback about the actuator actuation and ultimately about the actuation of the parking brake.

Other features, advantages and applications of the present invention will become apparent from the following description of exemplary embodiments of the parking brake systems according to the invention and their mode of action with reference to Figures 2 and 3. Here are all described and / or illustrated features alone or in any combination of the The subject of the present invention, also independent of their summary in the claims or their back references.

They show schematically:

1 shows a parking brake system according to the prior art,

Fig. 2 shows a first embodiment of a parking brake system according to the invention and

Fig. 3 shows a second embodiment of a parking brake system according to the invention. In FIG. 1, brake actuator 1 and brake actuator 2, which each serve to generate a parking brake force on a wheel of the motor vehicle, are connected in parallel to a central control unit 4 for the parking brake system of the motor vehicle via the voltage supply lines 3 and 6. About the vehicle bus 5, this central control unit 4 is connected to a control element, which is not shown.

In contrast, the parking brake system according to the invention shown in Figure 2 for each actuator 1, 2 each have a Radansteuerungseinheit RCUl, RCU2. The wheel control units RCU1 and RCU2 each contain essentially one or more microprocessors for processing the received signals or for generating signals, as well as power electronics, which serve to energize the respective actuator 1 or 2 connected to the wheel drive unit RCU1, RCU2.

Furthermore, a simple logical functional range of the prior art central control unit, which includes the detection of the driver's request and the detection of the vehicle speed, outsourced in the form of another control unit (ECU) 10, which may be integrated in other vehicle control units.

The further control unit 10 is connected in each case via a parking brake data bus (private bus) 11 or 12 to a wheel drive unit RCU1 or RCU2. The connections between the further control unit 10 and the Radansteuerungseinheiten RCUl or RCU2 parallel to each other.

Alternatively, a single parking brake data bus may be provided instead of the two individual parking brake data buses 11 and 12, which includes both parallel connections between RCU1 or RCU2 and ECU10. For this purpose, only a single transceiver for feeding the bus would be necessary in the further control unit 10, instead of two for the two parking brake data buses 11 and 12.

Furthermore, a safety data bus (vehicle bus 21 or vehicle bus 22) is provided for each wheel drive unit RCU1 and RCU2, which runs parallel to the parking brake data buses 11, 12 and connects one wheel drive unit RCU1 or RCU2 to the other control unit 10.

If a parking brake data bus 11 or 12 or both parking brake data buses 11, 12 now fails, the communication between the further control unit 10 and each drive unit RCU1 or RCU2 can take place via the respective safety data bus 21 and / or 22 and an actuation of the actuators 1, 2 is ensured, for example, when the driver expresses a parking brake request by means of the control element, not shown, and / or the vehicle is stationary. The operating element is in this case connected via the vehicle bus 5 with the further control unit 10. The information that the vehicle is stationary can be determined, for example, by measuring the wheel speed. The Processing of the corresponding data for this purpose can take place, for example, in the further control unit 10.

The illustrated in Figure 3 further embodiment of a parking brake system according to the invention has as means for ensuring the Aktuatorbetätigung in the event of a communication failure, two intelligent control / emergency control lines 31, 32 (instead of the vehicle buses 21 and 22). The control / emergency control lines 31, 32 each form a simple electrical connection between the further control unit 10 'and RCUl or RCU2, wherein the control / emergency control lines 31, 32 parallel to each other and each parallel to the respective parking brake data bus (private bus) 11 , 12 are lost.

If now the parking brake data bus 11 and / or 12 fails, then this state is noticed both by the further control unit 10 'and by the Radansteuerungseinheiten RCUl and / or RCU2, since the data bus communication does not work properly. In this situation, the operating state "emergency release" (emergency operation) is switched on. If the vehicle is stationary (the information about the missing vehicle movement can be forwarded to the further control unit 10 'via the vehicle bus 5, for example, or determined by the control unit 10' as described above), the further control unit 10 'generates by operating the control element Driver (EPB request) a predetermined safety signal sequence and sends it via the control / emergency control line 31 and / or 32 to the respective Radansteuerungseinheit RCUl and / or RCU2. The wheel drive unit RCU1 and / or RCU2 receive the signal safety signal sequence at their respective input and verify it. If the result of the verification is positive, a release command is forwarded to the respective actuators 1 and / or 2. An energization of the respective actuator 1, 2 takes place after the release command when, after verification of the safety signal sequence for a long time, preferably 2 seconds, a high signal via the respective intelligent control / emergency control line 31 or 32 to the respective Radansteuerungseinheit 1 or 2 is transmitted.

The safety signal sequence may preferably be in the frequency range between about 100 Hz to about 1 kHz.

The safety signal sequence (security code) can be protected against theft by designing the safety signal sequence according to the system time or by using a random generator to generate the safety signal sequence. In addition, the safety signal sequence can also be communicated to the wheel drive control unit 1 and / or 2 via the parking brake data bus. In the case of "emergency release" (emergency operation), the safety code that was last communicated via the parking brake data bus is then valid.

Reference symbol list:

1.2 actuator

3 Power supply actuator 1

4 central control unit of the parking brake system Drive train Power supply Actuator 2,10 'additional control unit (RCU), 12 parking brake data bus (private bus), 22 safety data bus (vehicle bus), 32 control / emergency control line

Claims

Claims:

1. Parking brake system for motor vehicles with a control element and at least two electromechanical actuators (1,2) for generating a parking brake force, in each case an actuator (1,2) is provided on each wheel of the motor vehicle, as well as with at least one Radansteuerungseinheit and another control unit, characterized in that each electromechanical actuator (1, 2) is respectively provided with a wheel drive unit (RCU1, RCU2), the further control unit (10, 10 ') being connected to the operating element on the one hand and via at least one parking brake data bus (11, 12) ) is connected in parallel with each Radansteuerungseinheit (RCUl, RCU2), wherein the further control unit

(10,10 ') the Radansteuerungseinheiten (RCUl, RCU2) with control signals applied and wherein means

(21,22,31,32) are provided which ensure the actuation of at least one actuator (1,2) even in the case of a communication failure in the system of the parking brake system.

2. Parking brake system according to claim 1, characterized in that at least one safety data bus (21, 22) is provided as the means for ensuring the actuation of the actuator, which controls the further control unit. unit (10) parallel to the parking brake data bus with each Radansteuerungseinheit (RCUl, RCU2) connects.

3. parking brake system according to claim 1, characterized in that at least one control / emergency control line (31,32) is provided as means for ensuring the Aktu- ator, which the further control unit (10 ') parallel to the parking brake data bus with a Radansteuerungseinheit ( RCUl, RCU2) connects.

4. Parking brake system according to claim 3, characterized in that the further control unit (10 ') comprises means in an emergency operation, preferably in case of failure of the parking brake data bus, a safety signal sequence and / or over a certain, fixed predetermined period , preferably over at least about 2 seconds, generate a high signal, wherein the safety signal sequence and / or the high signal via the control / emergency control line (31,32) to the respective Radansteuerungseinheit (RCUl, RCU2) is sendable.

5. Parking brake system according to claim 4, characterized in that each Radansteuerungseinheit (RCUl, RCU2) has means which receive the safety signal sequence at the input of the control / Notsteuerleitung (31,32) and then verify it and with a positive verification result an actuator operation allow .

6. Parking brake system according to claim 5, characterized in that the safety signal sequence is variable.

7. Parking brake system according to one of claims 4 to 6, characterized in that the actuation of the actuator (1.2) by the Radansteuerungseinheit

(RCUl, RCU2) takes place after receipt of the high signal at the input of the respective Radansteuerungseinheit (RCUl, RCU2).

8. Parking brake system according to one of claims 3 to 7, characterized in that each Radansteuerungseinheit (RCUl, RCU2) has means which generate after completion of the actuation of the actuator (1,2) an acknowledgment signal sequence, wherein the confirmation signal sequence about the respective tax

/ Notsteuerleitung (31,32) to the further control unit (10 ') can be sent.

9. Parking brake system according to one of claims 3 to 8, characterized in that the further control unit (10 ') and possibly each Radansteuerungseinheit (RCUl, RCU2)

Have means for generating an electrical signal.

10. A method for operating a parking brake system according to one of the preceding claims, characterized by the following steps: - monitoring communication in the parking brake system and initiating emergency operation if a communication failure is detected,

- Inserting the means (21,22,31,32) for actuating at least one actuator (1,2) in emergency operation when the driver actuates the operating element and / or the motor vehicle is.

11. The method according to claim 10, characterized in that the emergency operation comprises the adoption and implementation of the communication between the further control unit (10) and each Radansteuerungseinheit (RCUl, RCU2) by the safety data bus (21,22).

12. The method according to claim 10, characterized in that the emergency operation, the acquisition and implementation of the communication between the further control unit

(10 ') and each Radansteuerungseinheit (RCUl, RCU2) by the at least one control / emergency control line

(31,32).

13. The method according to claim 12, characterized in that, if the operating element is actuated by the driver and the vehicle operating state allows the parking brake to close, first by the further control unit (10 ') a safety signal sequence and then via a specific, fixed predetermined Period, preferably over at least about 2 seconds, generates a high signal and via the at least one control / emergency control line (31,32) is sent to the respective Radansteuerungseinheit (RCUl, RCU2).

14. The method according to claim 13, characterized in that each Radansteuerungseinheit (RCUl, RCU2) after receipt of the safety signal sequence by the input of the control / emergency control line (31,32) verifies this and allows actuator actuation at a positive verification result.

15. The method according to any one of claims 12 to 14, characterized in that each Radansteuerungseinheit

(RCUl, RCU2) after completion of the actuation of the respective actuator (1,2) generates a signal sequence, which via the at least one control / emergency control line

(31,32) is sent to the further control unit (10 ') and represents an acknowledgment of the actuator operation.